Photoluminescence and EBIC for Process Control and Failure Analysis in Si-Based Photovoltaics

Crystalline silicon used for fabrication of solar cells, such as multicrystalline silicon (mc-Si), contains a high density of extended crystal defects. Since mc-Si wafers exhibit an inhomogeneous defect distribution, there is a need to combine the spectral capabilities with the ability of spatially resolving the defect areas. This paper reports application of luminescence and electron-beam-induced current (EBIC) techniques for characterization of defects in solar Si. The first part introduces luminescence features of defective Si and discusses application examples. The second part starts with explanation of the EBIC technique, including details about the temperature dependence of the EBIC defect contrast c(T). Then, application examples of the c(T) behavior and the analysis of the "interaction" of grain boundaries with p-n junctions are discussed. The paper demonstrates the potential of luminescence for nondestructive characterization of Si wafers and solar cells in terms of in-line defect detection and process control.